Method for heating a solid surface such as a floor, wall, roof, or countertop surface

ABSTRACT

A method is provided for heating the surface of a material such as a floor, wall, roof, or countertop. The method comprises providing a laminated heater element, disposing the heater element at a predetermined depth in the material and energizing the element at prescribed intervals and temperatures which are effective to heat the surface of the material.

This application is a continuation of application Ser. No. 09/311,219,filed May 13, 1999 now U.S. Pat. No. 6,015,965, which is a divisional ofapplication Ser. No. 09/633,965, filed Apr. 19, 1996, now U.S. Pat. No.5,932,124, issued Aug. 3, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to methods of heating varioussolid surfaces. Specifically, the invention relates to methods ofheating floors, walls, roofs, or countertops by applying a heaterelement, such as a laminated composite heater element to the particularsurface and energizing the heater element.

2. Description of the Prior Art

A variety of heater elements exist in the prior art. U.S. Pat. No.4,534,886, to Kraus et al., discloses an electrically conductive webcomposed of a non-woven sheet of conductive fibers and non-conductivefibers. The sheet is saturated with a dispersion containing conductiveparticles and is then dried. The Kraus et al. heater element is usedprimarily in heating pads.

International Application No. PCT/US94/13504 (Publication No.WO95/15670) discloses an electrically conductive composite heatingassembly. The assembly has an electrically conductive non-woven fiberlayer laminated between layers of fiberglass and other dielectricmaterial. The assembly further has an abrasion resistant outer layer.The heater element is used on aerospace structures as an ice protectionsystem to withstand the repeated mechanical stress and thermal cyclesencountered in extremely harsh aerospace environments.

U.S. Pat. No. 5,344,696 to Hastings et al. discloses an integrallybonded laminate that is used to thermally control a surface of anaircraft to which the laminate is bonded.

None of the prior art heater elements, however, have been successfullyapplied to floors, walls, roofs, or countertops.

SUMMARY OF THE INVENTION

The present invention comprises a method for heating the surface of asolid material, such as a floor, wall, roof, or countertop. The methodcomprises providing a heater element, disposing the heater element at apredetermined depth in the material, and energizing the heater elementat prescribed intervals and temperatures, effective to heat the surfaceof the material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the construction of a composite heater element of theinvention in a mold.

FIG. 2 depicts a typical tile/paver floor containing the heater elementas described in the present invention.

FIG. 3 depicts a Formica™ counter top containing the heater element asdescribed in the present invention.

FIG. 4 depicts a typical heater element of the present inventionembedded within a solid surface material.

FIG. 5 depicts a roof ice dam heater of the present invention.

FIG. 6 depicts a typical inlaid concrete walkway containing a heaterelement as described in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention comprises a method for heating the surface of asolid material, such as a floor, wall, roof, or countertop. The methodcomprises providing a heater element, disposing the heater element at apredetermined depth and location in the material and energizing theelement at prescribed intervals and temperatures which are effective toheat surface of the material.

The heater element of the present invention is a laminated composite,impermeable to water, and is of the type disclosed in U.S. Pat. No.5,344,696 (Hastings et al.), which is incorporated herein by reference.As disclosed in the Hastings et al. patent, the heater element comprisesa durable outer ply, which is resistant to abrasion and impermeable towater, bonded to and through a conductive layer of fibers, and anintegrally enveloping adhesive, which is adhered to the surface of avessel. The conductive layer is connected to a source of electricalenergy, and control means are adapted to control the temperature of thesurface of the vessel. This laminated structure is consideredpreferable; however, it is contemplated that other structures may beused. For example, the heater element need not be a laminated structure.Rather, the heater element may comprise merely a layer of conductivefibers. This structure of the heater element is particularly-useful ifthe material into which the heater element is embedded has dielectricproperties that will evenly distribute the heat generated by theelement.

The preferred heater element is available under the trademark Thermion™,which is manufactured by Aerospace Safety Technologies, Inc. Thermion™is thin, light, flexible and may be translucent. The material is alaminate that provides even heating and can be conformed to surfaceshaving a variety of different contours and shapes. operational power canbe derived from low or high voltage AC or DC power supplies.

As discussed above, the heater element may comprise a layer ofconductive fibers that are directly embedded into the material. However,in this instance, the material must possess sufficient dielectricproperties to evenly distribute the heat generated by the fibers to thesurface of the material. Thermoplastic materials typically possess theseproperties.

The heater element is disposed at a predetermined location and depth inthe material. The depth and location may vary according to theparticular material and type of heating required.

1. Residential/Commercial Building Use

The thin, unobtrusive nature of the heater element makes it suitable foruse in ceramic and marble tile, solid surface materials, Formica,linoleum, and any other floor, wall, roof, or counter coveringavailable. The essential steps of the method of the present inventioncan be performed in several different ways.

A first variation in the method involves installing in the surface apre-made panel, usually configured on a mold table for easy transfer tothe final surface. As shown in FIG. 1, the pre-made panel comprises afiberglass resin encapsulated heater element 1, further encapsulated intwo fiberglass/resin cloths 5 and 5'. The pre-made panel also containselectrical leads attached to the heater element (not shown). Theelectrical leads extend outside of the panel and are attached to anelectrical power supply. The laminate optionally can be constructed withmultiple layers of the fiberglass resin encapsulated heater element 1.The multiple-layered heater element can provide greater control over theheat output from the assembly.

FIG. 1 shows how a single layer pre-made panel is formed on a transfertable. The fiberglass resin encapsulated heater element 1 is placed ontop of a mold table surface 9. A mold release wax 15 is disposed betweenthe encapsulated heater element 1 and the table surface 9. A peel ply 19is placed above the encapsulated heater element 1. A release ply 21 isdisposed above the peel ply 19 and a bleeder cloth 25 is disposed overthe release ply 21. Finally, a vacuum bag 29 is disposed over therelease ply 21. A seal tape 11 surrounding the layers on the mold isattached to the table top surface 9, and can adhere to the vacuum bag 29to create a tight seal. A vacuum supply 33 is used to evacuate the airbetween the layered material in order to bring the layers into closecontact with each other and cure the resin, bonding the layers to createthe laminate.

Referring to FIG. 2, a pre-formed panel may be installed below a varietyof covering surfaces, such as ceramic, marble, or similar paver tiles.In a tile and grout environment 101, the sub-base, whether a floor orcountertop, may first be covered by a particle board underlayment 100.Some builders choose not to use an underlayment, but its purpose is toaid in leveling the floor and build uniformity. A vapor barrier and oneor more concrete base products are then applied over the underlaymentset. At a minimum, the concrete 102 should be at least 1/2 inch thickfor standard wet/dry environments, such as kitchen and bathroom floorsand counters (see FIGS. 2 and 3). For standing water conditions, such asshowers and exterior areas, the layer must be at least twice thisthickness. Concrete serves a dual purpose. It limits the surface flexingand also acts as a water barrier. The vapor barrier further preventswater from passing to the wood below either by sweating or cracking ofthe concrete. A heater element 104 is disposed above the concrete base102. The heater element 104 optionally contains a syntactic film layer106 on the back/bottom side for bonding the element 104 to the concretebase 102. Film layer 106 replaces the mastic that would otherwise berequired to set heater element 104 in place. Without a bonding filmlayer, the installer would smear the concrete base with a thin layer ofmastic, alternatively referred to as 105, apply the heater element fromedge to edge, minimizing air pockets, and roll the element flat againstthe concrete base 102. Once the heater element 104 is set, the normalprocess of installing tiles 101 can continue. If necessary, the panelmay be punched with suitable tools to create holes or other shapes, asneeded, and edge finished to protect against electrical shock. Theholes, depending on their relative size and location, will have minimalto moderate effect on the heat output of the device.

As depicted in FIG. 3, the heater element 104 can be installed under acountertop layer 108, such as a Formica or linoleum top layer, in amanner similar to tile, although the concrete base and vapor barrier areno longer required. In addition, Formica/linoleum installation generallyutilizes contact adhesives which require additional processing known tothose skilled in the art.

A second variation in the method of the present invention involvessimultaneously constructing the composite heater element 104 at the timethe floor, wall, roof, or countertop material is constructed. Forinstance, the composite in FIG. 3 may be constructed on the subsurface109 simultaneously as the other layers of material are applied over theheater element 104. This second method is particularly useful in theconstruction of formica and metal countertops. This-method isadvantageous in that custom-shaped heater elements may be easilyincorporated below the finished surface of the material. For example, inthe case of wood/concrete substrates, custom-shaped heater elements maybe bonded under the finished surface of the material. In carrying outthis method, the heater element is disposed on a solid, clean surface,and epoxy resin is applied to bond the element to the material. Thecomposite may also be vacuum cured and heated, if desired. The vacuumprocess regulates the heater resin content in conjunction with thefiberglass selected. After the curing process is complete, the topsurface of the material may be finished, as desired. In the case ofFormica, a contact adhesive is applied between the element and the topsurface before they are joined. Thereafter, the composite is rolled tocomplete the process.

As depicted in FIG. 4, a third variation in the method of the presentinvention involves providing a heater element 104 without the fiberglassouter layers or resin and encapsulating the element 104 within thefinished material at the factory/production level. Such an installationis suitable for solid surface 112 materials such as Corion®, or anyother thermoplastic formed item that has sufficient dielectric strengthto isolate the electric heater element from the surface, and that allowscohesive bonding through the heating element. Most structures developedby liquid process molding are excellent candidates. The placement of theheater element 104 can be accurately controlled providing heat as nearto the surface as is practical and safe. Using standard counter depths,the heaters can be pre-formed to run front to back allowing the surfaceto be cut to length, and end finished. A front to back orientationrefers to the direction of current flow.

Different configurations of heater placement and orientation may beaccomplished at the time of production, allowing for custom needs. Somecircumstances may require surface heating in localized areas, forinstance, the areas around a sink or other fixtures. The heater elementmay, therefore, be precut to any particular pattern and may containholes or cuts, as is necessary. For a field modification to a solidsurface application, the surface could be cored within certaindimensions and edge finished, having minimal to moderate effect on theheater's performance.

Additional residential/commercial building applications include roofde-icing as shown in FIG. 5 and concrete walkways as shown in FIG. 6.These applications could use the pre-made panels for convenience andquick installation. Such roof applications are suitable for neoprene,hot mopped, shingled or even metal style roofs. FIG. 5 shows a typicalapplication of the heater element 104 to a roof. Listed from bottomlayer to top layer, the typical heater roof comprises a wood sheetingsubstrate 109, felt paper 113, heater mastic 111, the heater element104, and the finished roof layer 115. The finished roof layer 115 may beof typical roof finish materials such as, neoprene rubber, metal, or thelike.

Application of the heater element in a concrete walkway is depicted inFIG. 6. The walkway contains a perforated panel 114, laid duringconstruction over and above, or in place of, a remesh/rebar 116. Theheater element 104 is disposed over the perforated panel 114. Finally, atop layer of concrete is disposed above the element.

The heater element may also be applied to rain gutters. Such applicationmay be completed by use of any of the methods discussed. The particularmethod chosen depends on the installation and gutter product selected.

Additionally, the heater element may be applied to mirrors. Mirrorapplication to prevent fogging is an example of a simple back sidebonding. The heater may be a pre-formed panel or a formed-in-placeinstallation. For radiant heat applications the methods are no differentonly the object selected to encase the material vary. Besides thepossibility of heated pavers, diffused panels for a green house canincorporate the heated panels. The panels can be of simple or complexdesign and may provide winter environmental control and snow removal.Additional greenhouse installations could provide local heating as wellfor particular applications, such as lighting pairs for ice/snowprotection and for heating/environmental control.

What is claimed is:
 1. A method for heating a wall, comprising;providinga pre-formed panel heater element to the wall, wherein said pre-formedpanel heater element consists of an inner layer composed of a fabric ofelectrically conductive fibers encapsulated between two fiberglass/resinlayers: two outer fiberglass/resin layers disposed on opposing surfacesof said inner layer and encapsulating said inner layer; and electricalleads connected to said conductive fibers and adapted to receive powerfrom a power source; disposing the pre-formed panel heater element at apredetermined depth in the wall; and energizing the conductive fibers ofthe pre-formed panel heater element at prescribed intervals andtemperatures which are effective to distribute heat evenly on thesurface of the wall.
 2. The method of claim 1, wherein the wallcomprises ceramic, paver or marble tiles.